Download Frequency lowering hearing aids: New techniques for fitting

Frequency lowering hearing aids:
New techniques for fitting
Susan Scollie, Ph.D.
Associate Professor
Child Amplification Laboratory
School of Communication Sciences and Disorders
National Centre for Audiology
University of Western Ontario
Historical evolution:
• Earliest attempts
60’s 70’s • Not all were real time
80’s 90’s
2000’s
• Early commercial products
• First nonlinear frequency compressors
• Ongoing development of multiple types of
frequency lowering
Clinical uses of Frequency lowering?

Frequency lowering can be
used to overcome
bandwidth limitations of:
◦ The ear
◦ The device

What cues are missing if
you cannot hear above 2k?
Frequency Lowering (FL): three types

Frequency
Compression (FC)
◦ Phonak SoundRecover®
◦ Siemens FC

Frequency
Transposition (FT)
◦ Widex
AudibilityExtender ®

Frequency
translation
◦ Starkey Spectral IQ ®
Below cutoff
Above cutoff
Frequency (Hz)
Below cutoff
Above
cutoff
Frequency (Hz)
Below cutoff
Above
cutoff
Frequency (Hz)
Frequency Lowering (FL): three types

Frequency
Compression (FC)
◦ Phonak SoundRecover®
◦ Siemens FC

Frequency
Transposition (FT)
◦ Widex
AudibilityExtender ®

Frequency
translation
◦ Starkey Spectral IQ ®
Below cutoff
Frequency (Hz)
Below cutoff
Frequency (Hz)
Below cutoff
Above
cutoff
Frequency (Hz)
Why might we use it?
What happens if I use frequency
lowering?
Does it help and for whom?
For reprints of published work, go to:
http://www.dslio.com/page/en/pubs_downloads.html
Outcomes in adults and children:
24 patients: 11
children and 13
adults
 Phonak frequency
compression (precommercial, ear
level devices)

Glista et al (2009a), IJA, (2009b)
Hearing Review
Support: NSERC-CIHR CHRP, Hearing
Foundation of Canada, Phonak AG
Our adults with High Frequency
Hearing losses > 65 dB HL:

4 out of 6 improved in S or SH detection
◦ 1other was poorer, 1 had no change

4 out of 6 improved in detection of wordfinal plural cues (e.g., book vs. books).
◦ Two of these had significant double blinded
preference for frequency compression.
◦ The other two had no preference for either
frequency compression or conventional.
Our adults also rated the sound
quality of female speech:
Peak clipped
speech has
poor sound
quality.
The original
stimulus is
rated as having
high sound
quality.
(Parsa et al, accepted)
Our adults also rated the sound
quality of female speech:
Medium
strength FC
has high sound
quality, for HI
adults.
Strong FC has
poorer sound
quality.
(Parsa et al, accepted)
Other sound quality results:

Sound quality declines gradually
across the range of cutoff frequencies
from about 3000 Hz to about 1600
Hz.
◦ No abrupt steps in sound quality change
◦ More noticeable for female speech
◦ Implications for fine tuning?

For speech in noise and for music,
listeners with hearing loss rated
fewer changes in sound quality than
they did for speech in quiet.
(Parsa et al, accepted)
Acclimatization?

6 participants (11-18 years)
◦ DSL5 at baseline trial
◦ Four month trial with
frequency compression,
no training.


Some participants had
significant
acclimatization trends: 6
to 8 weeks.
May relate to degree of
hearing loss?
Glista, Scollie, and Sulkers (2012, JSLHR)
Support: CIHR Banting & Best, Phonak AG
FINE TUNING
FREQUENCY
COMPRESSION?
Testing multiple FC settings:

21 adults (mean age
66, range 25-87 years)
◦ 14 were hearing aid
users
◦ 5 had frequency
lowering hearing aids
3 with dead regions
 Fitted with DSL5,
verified with speech in
the ear canal.

◦ FC off + 5 FC strengths
Support: Phonak AG
Study Design

Settings (6 in total):
◦ Off, default, strongest, and:
 100 Hz separation between S and SH
 300 to 500 Hz separation
 > 500 Hz separation
◦ Randomized presentation order, no trial period

Outcome measures
◦ Detection of word-final fricatives (2 AFC, 60 dB SPL)
◦ Discrimination of /s/ and /sh/ (3 AFC, 65 dB SPL)
◦ Recognition of consonants (21 AFC, 65 dB SPL)
Outcomes:
Glista, Scollie, et al (in preparation)
Is discrimination of /s/ and /sh/ predictable
from real ear measurement?
Is detection of word-final frication predictable
from real ear measurement?
Normal
performance
Clinical implications:

Verification results are related to
outcomes.
◦ Audibility for “S” is associated with good
detection of word-final /s/.
◦ S can be slightly below threshold and still
heard… due to broadband effects.
◦ At least 200 Hz separation of S and SH is
needed for good s-sh discrimination.
 Separation may be at peak or at shoulder.
Let’s practice reading fittings
Remember, we want:
•
S to be at least close to threshold, preferably 5 dB
sensation level.
•
S and SH should be separated by at least 200 Hz in
frequency, preferably 500 Hz.
Here’s the test signals:
SH
S
SoundRecover off:
SH
S
SoundRecover A:
S
SH
SoundRecover B:
SH
S
SoundRecover C:
SH
S
Fine tuning lessons learned?

The hearing aid’s gain and FC interact:
◦ If you have less high frequency gain, you will
need to use a stronger FC setting to make S
audible.
◦ FC strength is correlated with sound quality
changes… use the weakest setting you can
that has positive effects.
◦ Fine tuning is possible.
◦ Verification and real ear measurement is
possible and meaningful… but new.
Clinical implications

Have a look at Glista &
Scollie, 2009,
AudiologyOnline and give
fine tuning a try!
◦ It shows a “speech bands” test
signal and live s - sh.
◦ Same principles as discussed
today.
Clinical implications

Interested in knowing if people can hear new
sounds with frequency lowering?
Interested in knowing if your extended
bandwidth fittings are providing access to /s/
without frequency lowering?

New clinical test:

Glista, D. and Scollie, S. (2012). Development and
Evaluation of an English Language Measure of Detection
of Word-Final Plurality Markers: The University of
Western Ontario Plurals Test. American Journal of
Audiology, 21: 76-81.

Colleagues and support



Thanks to the organizing committee!
Project coordinator for this work: Danielle Glista, Ph.D.
Lab members and NCA Colleagues:
◦ Vijay Parsa, Paula Folkeard
◦ Andrea Dunn, Melissa Polonenko, Jacob Sulkers, Julie Seto
◦ Sheila Moodie, Marlene Bagatto, Viji Easwar

Research Funding and Collaboration: Phonak for ongoing support
and Widex for project collaboration. Past support from Mason’s
Foundation of Ontario, CIHR, and NSERC.
References
Glista, D., & Scollie, S. (November, 2009). Modified Verification Approaches for Frequency
Lowering Devices. Audiology Online, 1-11. Retrieved from
http://www.audiologyonline.com/articles/article_detail.asp?article_id=2301
Glista, D. and Scollie, S. (2012). Development and Evaluation of an English Language Measure
of Detection of Word-Final Plurality Markers: The University of Western Ontario Plurals
Test. American Journal of Audiology, 21: 76-81.
Glista, D., Scollie, S., Bagatto, M., Seewald, R., Parsa, V., & Johnson, A. (2009). Evaluation of
nonlinear frequency compression: Clinical outcomes. International Journal of Audiology,
48(9), 632-644.
Glista, D., Scollie, S., Polonenko, M., & Sulkers, J. (2009). A comparison of performance in
children with nonlinear frequency compression systems. Hearing Review, 16, 20-24.
Glista, D., Scollie, S., & Sulkers, J. (in press). Perceptual acclimatization post nonlinear
frequency compression hearing aid fitting in older children. Journal of Speech, Language,
and Hearing Research. Vol. 55,1-23 .
Parsa, V., Scollie, S., Glista, D., Seelisch, A. (accepted). Nonlinear Frequency Compression:
Effects on Sound Quality Ratings of Speech and Music, Trends in Amplification.
Real Example: Tuning
Scollie & Glista (2011) ENT & Audiology News
And the winner is…
Test
Nonsense syllables
Discrimination of S/SH
Percent
Correct
Score
Setting 1
56%
37%
Percent
Correct
Score
Setting 2
Interpretation
69%
Significant improvement with the
revised setting
65%
Significant improvement with the
revised setting
FAQS…
1. When should I enable FC in a fitting?

Some important considerations:
1. Is the listener receiving sufficient audibility across frequencies
without using frequency lowering?
 Start with a scientifically based prescriptive method to assess fitto-targets (i.e., provide as good of a fitting as possible without NFC
enabled)
2. Have you verified this using appropriate techniques? (e.g., using
advanced verification techniques)
3. Consider the literature! Aim to provide audibility of energy
well above 4000 Hz for developing infants & children (refer to
start of presentation) – what we can accomplish with
conventional amplification is ever evolving!
2. Should we be providing asymmetrical NFC
settings?
Studies thus far include symmetrical NFC settings
only (i.e., the same NFC setting in each ear, with the
exception of one published case)
 This included fitting NFC based on “better ear”
thresholds
 What would an asymmetrical NFC setting mean for
the listener? They would be receiving asymmetrical
frequency allocation between the two sides… Can
the listener adapt to this?
 We need more research to directly evaluate how
this will affect speech understanding

3. Is it ok to enable NFC for mild to moderate
hearing losses?



Studies on this topic have included listeners with mild to
moderate PTA values and significantly more hearing loss
in the high-frequencies (i.e., moderately severe to
profound in the high-frequencies)
We do not have any evidence suggesting that NFC
technology should or should not be used in cases
presenting with a mild amount of hearing loss in the highfrequencies
Think back to FAQ #1
◦ Aim to provide FC in the case where a conventional fitting cannot provide
sufficient audibility of high-frequency sounds
◦ Err on the side of providing frequency compression to only the highest
frequency part of each fitting

Further research is needed - for discussion on this topic
refer to: Scollie (ASHA Division 9, 2010), Wolfe et al. 2010